Retractable double blade knife



FIG. 1 is a right side elevational view of a retractable double blade knife showing our new design;

FIG. 2 is a top plan view thereof.

FIG. 3 is a left side elevational view thereof.

FIG. 4 is a bottom plan view thereof.

FIG. 5 is a front elevational view thereof, the rear view being substantially the same. 

The ornamental design for a retractable double blade knife, as shown and described. 